Output of Cursor

I use Oracle 10g. In SQL*Plus Worksheet, I created the following procedure
which didn't produce any errors during creation:
CREATE OR REPLACE PROCEDURE test(x IN FLOAT, myres OUT SYS_REFCURSOR)
is
BEGIN
OPEN myres FOR
SELECT *
FROM TESTTABELLE
WHERE x >= cos(pi/180.0);
END test;

My problem is now: How do I have to call this procedure from SQL*Plus
Worksheet?
call test (2.7, NULL); for example gives me error ORA-06553. I think
because of the NULL.
I just want to call the procedure and get somehow displayed the content of
my cursor "myres" in SQL*Plus Worksheet.